[time-nuts] SMPS or conventional?

[Skip Withrow]

Hello Time-Nuts,
Though this thread started out asking about power supplies, it seems
to have morphed into a Rb cooling discussion as well.

I undertook a similar PRS-10 project a while back.  Since the PRS-10
uses an SC cut crystal and has decent phase noise for a small rubidium
I went the linear regulator route to try and preserve the 'goodness'.

For cooling, I hate fans.  They are noisy, they fail, and they
generate magnetic fields.  So, I sandwiched a couple of TEC coolers
between the PRS-10 and a heat pipe unit from an old server.  I have an
AD590 sensor and simple control circuit that keeps the baseplate at a
controlled temperature and the heat is transported out to the back of
the box and dissipated by convection. I love it.

My only complaint is the resolution of the PRS-10.  Everything goes
through the uP, including the EFC voltage, and the minimum DDS
resolution is about 2x10E-12.  So you will never get anything better
than a good GPSDO anyway.  Might as well stick with the GPSDO with a
good oscillator, unless you actually need some long-term holdover
performance.

Regards,
Skip Withrow